JPH03189013A - Manufacture of inner surface worked heat transfer tube and its device - Google Patents

Abstract

PURPOSE:To manufacture the internally finished heat transfer tube of excellent heat transferring property by specifying the relation among the thread roll forming pitch a whole length of tube material to be pressed to the plug surface with groove and the length of the tube material to be subjected to sufficient transferring of the projection and recession of the plug. CONSTITUTION:The thread roll forming tool 5 presses the tube material 1 to the plug with groove 3 positioned at the inner surface of the tube material 1 and projecting and recessing work is executed. In the state where the thread roll forming pitch P, the whole length L of the tube material 1 to be pressed to the surface of the plug with groove with the thread roll forming tool 5 and the length L2 of the tube material 1 to be subjected to sufficient transferring of the projecting and recessing surface of the plug with groove 3 with one of thread roll forming tool 5 are set in the range of L2<P<L, the tube material 1 is moved. The insufficiently transferred part L1 of the surface of the plug to the tube material 1 remains at final, and the projecting and recessing parts of the projecting part 61, the groove 63 and inclining part 63 are formed on the inner surface of the tube material 1. The heat transferring property can be improved without increasing pressure loss of the tube being so much.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for manufacturing internally processed heat exchanger tubes used in heat exchangers for refrigerators, air conditioners, etc.
The present invention relates to a method for manufacturing a boiling or condensing type internally processed heat exchanger tube in which a refrigerant is boiled or condensed inside and heat exchanged with a fluid outside the tube.

``Prior Art'' As shown in FIG. 7, there is a floating plug 2 with a rod 21 attached to the center, and a spiral wire rotatably held at the tip of the rod 21 and having a predetermined helix angle with respect to the axis on the outer periphery. A grooved plug 3 with a large number of shaped grooves formed therein is inserted into a predetermined position inside the metal tube 1, and while the tube 1 is pulled out to the right in the figure, the floating plug 2 and the diameter reducing die 4 work together. The diameter of the tube material 1 is reduced by pressing the tube material 1 against the surface of the grooved plug 3 using a plurality of rolling tools 5 consisting of rolls that rotate planetarily around the outer periphery of the tube material 1 at the position of the grooved plug 3. A technique for manufacturing a heat transfer tube by machining a large number of grooves 1O on the inner surface of the tube material 1 and dry-drawing the tube material 1 with a finishing die (not shown) is disclosed, for example, in Japanese Patent Application Laid-Open No. 54-370.
It is publicly known as disclosed in Japanese Patent Publication No. 59 (Japanese Patent Publication No. 61-59806).

Further, after forming the groove 10 as described above on the inner surface of the pipe material 1,
A technique is also known in which a number of other grooves (not shown) intersecting with the groove 10 are formed in the tube material 1 by means similar to the grooved plug 3 and the rolling tool 5.

The process of forming the grooves 10 on the inner surface of the tube material l using the conventional method and apparatus for manufacturing heat exchanger tubes with internal processing explained in FIG. 7 will be explained with reference to FIGS. 8 and 9. The tool 5 is brought into pressure contact with the surface of the tube 1 while drawing a spiral locus by its revolution and the drawing of the tube 1. As shown in FIG. 8, when the tube 1 is pressed onto the surface of the grooved plug 3 by one rolling tool, the portion A of the tube 1 at the pressed part
~C, the amount of metal pushed into the groove depth d of the three-grooved plug 3 gradually increases along the pulling direction so that the unevenness on the surface of the grooved plug 3 is easily transferred to the inner surface of the tube material l. In portions A to E, the pushing amount is constant and maximum.

As a result, as shown in an enlarged view in FIG. (the length of contact between the tube material l and the surface of the plug 3 at the pressed portion), a portion L1 where the unevenness of the surface of the grooved plug 3 is insufficiently (incompletely) transferred at the rear end in the pulling direction of the tube material 1; Continuing from this, a portion L2 is formed in which the unevenness is sufficiently (completely) transferred.

Portions A to E of the tube l in FIG. 8 correspond to portions 11a to 11e of the protrusions 11 in the tube l in FIG. 9, but as shown in FIG. Article 11
The portions 11a to llc are inclined upwardly along the drawing direction A of the tube material 1, and the adjacent portion where the groove 1o begins to be formed is, conversely, inclined downwardly along the drawing direction A. . Then, after the first rolling tool 5 presses the pipe material l at the installation position of the grooved plug 3, the pipe material l is pulled out while the next rolling tool that rotates planetarily presses the pipe material. Because the distance, that is, the rolling pitch P, is smaller than the length L2 at which the unevenness on the surface of the grooved plug 3 is sufficiently (completely) transferred by one rolling tool 5,
The convex strips 11 and the grooves 10 were insufficiently transferred into the pipe material 1 by one rolling tool 5, and the next continuous rolling tool presses the pipe material 1, resulting in the above-mentioned defect. The sufficient transfer portion 11 is also formed with sufficient transfer in the same way as the portion L2.

That is, with respect to the pipe material 1 moving in a fixed direction in this way, since a plurality of rolling tools planetarily rotate the same part on the grooved plug 3 and press it back, the plug 3 as a whole is pressed.
The unevenness is completely transferred in the longitudinal direction of the tube material 1, and grooves 10 and protrusions 11 having the same cross section are continuously formed on the inner surface of the tube material 1.

The cross-sectional shapes of the grooves 10 and the protrusions 11 are determined by the cross-sectional shapes of the grooves formed on the outer periphery of the plug 3, and various improvements have been made to these cross-sectional shapes.

``Problem to be solved by the invention'' With the spread of heat pump air conditioners in recent years, there has been a strong demand for higher performance and smaller and lighter heat exchangers for air vRm. Depending on the conventional method and device, only grooves and protrusions of a specific shape are alternately formed on the inner surface of the tube, and there is a limit to the improvement of heat transfer performance.

In addition, forming grooves and protrusions on the inner surface of the tube using the two sets of grooved plugs 3 and rolling tool 5 increases the pulling load on the tube, and unless the pulling speed is extremely slow, the tube will break. Therefore, manufacturing cost increases.

It is an object of the present invention to avoid major modification of existing manufacturing equipment and to reduce manufacturing costs compared to the existing method and equipment as shown in FIG. 7.

It is an object of the present invention to provide a method for manufacturing a heat transfer tube that has far better heat transfer performance than conventional inner grooved tubes.

"Means for Solving the Problems" In order to achieve the above-mentioned object, the method for manufacturing an internally processed heat exchanger tube according to the present invention involves inserting a grooved plug having a large number of grooves formed on the outer periphery into a predetermined position within the tube material. While moving the tube material in a certain direction along the tube axis, the outer periphery of the tube material is brought into contact with the outer peripheral surface at the position of the grooved plaque using a plurality of rolling tools made of rolls or balls that rotate planetarily. In the method for manufacturing a heat exchanger tube, in which unevenness is formed in the tube material by pressing the tube material from the outer periphery onto the surface of the grooved plug, a subsequent pressing step of the tube material by one rolling tool on the surface of the grooved plug is provided. The distance that the pipe material moves while the next rolling tool presses the pipe material, that is, the rolling pitch P, the total length of pressing the pipe material against the grooved plug surface by one rolling tool, and the first rolling tool. L2 is the length L2 at which the unevenness of the grooved plug surface is sufficiently transferred to the pipe material by the pressure of
2<P.

It is characterized in that the tube material ° is moved in a state set within the range of the equation of <L.

Preferably, the grooved plug is configured such that its position relative to the tube axis can be finely adjusted by appropriate means.

"Operation" According to the manufacturing method according to the present invention, on the surface of the grooved plug, one rolling tool presses the pipe material over the entire length, and one rolling tool creates unevenness on the surface of the grooved plug inside the pipe material. is sufficiently transferred, and the distance that the pipe material moves after one rolling tool presses the pipe material and the next rolling tool presses the pipe material, that is, the rolling pitch P. , L
When the pipe material is moved within the range of the formula 2<P<L, as shown in FIG. 9, the unevenness on the surface of the grooved plug is insufficiently transferred to the inner surface of the pipe material by one rolling tool. As a result, between each groove formed on the inner surface of the pipe material, there is a sloped part that slopes in the same direction (upward in the direction of movement of the pipe material) at the top along the longitudinal direction. ridges of a predetermined length are repeatedly formed, and at the bottom of each of the grooves, an inclined surface that slopes in a direction opposite to the slanted portion of the ridged portion is provided along the longitudinal direction at each adjacent portion to the slanted portion. It is formed repeatedly.

In other words, the inner surface of the tube has countless fine irregularities, and these irregularities improve heat transfer performance.

The repeated slopes formed on the ridges and groove bottoms produce a heat exchanger tube in which the pressure loss within the tube is almost the same as that of conventional internally grooved tubes.

"Example" FIG. 1 is a sectional view showing an example of a manufacturing apparatus for explaining an example of the method of the present invention.

A cup-shaped die holder 42 is inserted into the cup-shaped fixed base 41 with the open end partially protruding, and a diameter-reducing die 4 through which the metal tube 1 is passed is fixed in the die holder 42. There is.

A screw 43 is formed on the outer periphery of the open end of the die holder 42, and a nut-shaped stopper 40 is screwed onto the outer periphery of the open end, and this stopper 40 prevents the die holder 42 from escaping from the fixed base 41. There is.

Inside the diameter reducing die 4, there is a 70 mm inserted into the pipe material l.
- A floating plug 2 is provided, and the rod 21 fixed to the axis of the floating plug 2 has a tube attached to its outer periphery so as to be located in front of the floating plug 2 (in front along the drawing direction A of the tube material l). A grooved plug 3 having a large number of spiral grooves 31 with a helical angle of 18 degrees relative to the shaft is rotatably held.

At the installation position of the grooved plug 3, three rolling tools 5 made of rolls that rotate planetarily and press the outer circumference of the pipe material 1 into contact with its outer circumferential surface are provided at equal angular intervals. In the example, each rolling tool 5 causes a grooved plug 3
The length for pressing the pipe material 1 onto the surface, that is, the total length for pressing the pipe material l onto the surface of the grooved plug 3 with the first rolling tool 5, is 2.1■, 3 Length L2 force (3
, 8+ua, insufficiently transferred length Ll force < 1.3 m
■The distance that the pipe material moves from pressing one rolling tool 5 to the pipe material 1 on the surface of the plug 3 until pressing the next rolling tool 5, that is, the rolling pitch P is 2 m. The number of revolutions of the rolling tool 5, the drawing speed of the pipe material, and the positional relationship between the grooved plug 3 and the rolling tool 5 are set.

The screw 43 at the open end of the die holter 42 and the stopper 40 screwed thereon constitute a fine adjustment means 4a for finely adjusting the axial position of the plug 3, and by turning the snout-shaped stopper 40, This structure allows the plug 3 to be moved slightly in the axial direction to adjust the contact length. This fine adjustment means 4a may have another structure.

In the manufacturing apparatus, a blank drawing die (not shown) is provided in front of the installation position of the rolling tool 5 (in front of the direction in which the tube material 1 is pulled out).

If the pipe material 1 does not need to be reduced in diameter,
The floating plug 2 and diameter reducing die 4 are unnecessary, and in this case, the end of the lot 21 is supported by a member (not shown) located outside the tube material 1.

A drawing machine (not shown) pulls out a copper tube 1 at a constant speed in the direction of arrow A in FIG. The diameter of the diameter-reduced pipe material 1 is further reduced by the rolling tool 5 that revolves at the rolling pitch and the grooved plug 3, and at the same time, the number of grooves in the cross section on the inner surface is 60. Grooving was performed so that the helix angle of the groove with respect to the tube axis was 18 degrees, and dry drawing was performed using a dry drawing die (not shown) to produce an internally processed heat exchanger tube with an outer diameter of 9.53 m1+.

As shown enlarged in FIG. 2, the maximum wall thickness at the top between the grooves 60 on the inner surface of the heat exchanger tube 6 is approximately 0.45 mm.
mm, and sloped in the same direction at the top along the groove 60 (sloped upward in the pulling direction A of the tube material 1 during manufacturing).
A raised portion 61 having a substantially constant length is repeatedly formed, and at the bottom of each groove 60, a portion of the raised portion 61 adjacent to the sloped portion 61 is sloped in a direction opposite to the sloped portion 62. Inclined surfaces 63 were repeatedly formed along the longitudinal direction.

Maximum groove bottom thickness tax is 0.3mm, minimum groove bottom thickness tm
in was 0.25 mm. The locus in which the stepped portions between the raised portions 61 and the stepped portions between the inclined surfaces 63 in the groove 6o are formed has a spiral shape with respect to the tube axis.

The heat exchanger tube manufactured by the manufacturing method of this example and the internally grooved heat exchanger tube (outer diameter 9.53 mm) manufactured by the conventional manufacturing method
, number of grooves: 60, groove helix angle: 18 degrees, groove depth: 0.2 mm)
were incorporated into a double-tube heat exchanger, and the evaporative heat transfer coefficient and condensation heat transfer coefficient within the tubes were measured, and the results shown in Figs. 4 and 5 were obtained. According to this result, the heat exchanger tube manufactured by the manufacturing method of the above example has an evaporation performance of about 60% compared to the internally grooved heat exchanger tube manufactured by the conventional method.
, condensing performance °C has improved by about 40%.

In addition, when comparing the pressure loss inside the tube, it was found that it was almost the same as that of the internally processed heat exchanger tube manufactured by the conventional method.

The rolling pitch P is set in the same manner as in the above embodiment, and the contact length between the grooved plug 3 and the pipe material 1 at the pressed part of the pipe material 1 (
When heat exchanger tubes of similar size were manufactured by changing the total pressing length (length) L by the first rolling tool 5, the length L2 at which the unevenness on the surface of the plug 3 was sufficiently and completely transferred was determined. , the major groove bottom thickness t+iax and the minimum groove bottom thickness twi
The relationship with the difference in n is shown in Fig. 4, and when other conditions are held constant, the protrusion 61 and The size of the step of the groove 60 can be selected.

Furthermore, during mass production, by adjusting the axial position of the plug 3 WL to adjust the length of the pressing portion, it is possible to continue to form countless irregularities stably on the inner surface of the tube.

If the length L2 at which the unevenness on the surface of the grooved plug 3 is sufficiently transferred by the pressure of the first rolling tool is set to zero or ζ or close to zero, the slope of the protrusion 61 as shown in FIG. The inclined surfaces 63 of the portions 62 and the grooves 60 can be formed in a continuous step-like manner.

It should be noted that the manufacturing method according to the present invention is not limited to the above-mentioned embodiments, but can be implemented with appropriate changes within the scope of the claims.

"Effects of the Invention" According to the method for manufacturing a heat exchanger tube according to the present invention, it is possible to manufacture an internally processed heat exchanger tube with better heat transfer performance without significantly increasing the pressure loss inside the tube, and moreover, With only slight improvements to the equipment, it can be manufactured at low cost.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a manufacturing apparatus for explaining an example of the manufacturing method according to the present invention, FIG. FIGS. 4 and 5 are partially enlarged exploded perspective views showing other examples of heat exchanger tubes manufactured by the method of the invention, and FIGS. Figure 6 shows the difference between the maximum groove bottom thickness and the minimum groove bottom thickness of the inner groove and the difference in the inner surface of the tube material when heat transfer tubes are manufactured by the method of the embodiment of the present invention. Grooved flap. A line diagram showing the relationship between the length and the length to which the unevenness of the lug surface is sufficiently and completely transferred. Figure 7 is a sectional view showing an apparatus for explaining the conventional manufacturing method. FIG. 9 is a partially enlarged sectional view showing the process of forming uniform grooves and protrusions on the inner surface when manufacturing a heat exchanger tube. FIG. FIG. Explanation of main symbols in the figure 1 is a tube material, 2 is a floating plug, 3 is a plug with many grooves on the outer periphery, 4 is a die for diameter reduction, 4a is a fine adjustment means, 40 is a stopper, 42 is a die holder, 5 is a die holder A rolling tool, 6 a heat exchanger tube, 60 a groove, 61 a raised part, 62
is the inclined part, 63 is the inclined surface, P is the distance that the pipe material moves while the next rolling tool presses the pipe material following the pressing of the pipe material by one rolling tool on the surface of the grooved plug,
That is, the rolling pitch, L is the total length of pressing the pipe material against the grooved plug surface by one rolling tool, and L is the length of the grooved plug surface that is insufficiently uneven against the pipe material due to the pressure of the first rolling tool. The length to be transferred, L2, indicates the length at which the unevenness on the surface of the grooved plug is sufficiently transferred to the pipe material by the pressure of one rolling tool.

Claims (2)

[Claims] (1) A grooved plug with a large number of grooves formed on the outer periphery is inserted into a predetermined position inside the tube material, and while the tube material is moved in a certain direction along the tube axis, the outer periphery of the tube material is inserted at the position of the grooved plug. A method for manufacturing a heat exchanger tube, in which the tube material is pressed from the outer periphery onto the grooved plug surface using a plurality of rolling tools made of rolls or balls that rotate planetarily while in contact with the outer peripheral surface of the tube material to form irregularities in the tube material. , the distance that the pipe material moves while the next rolling tool presses the pipe material following the pressing of the pipe material by one rolling tool on the surface of the grooved plug, that is, the rolling pitch P; a total length L of pressing the pipe material onto the grooved plug surface with a rolling tool;
L2<P<L2<P<
A method for manufacturing an internally processed heat exchanger tube, characterized in that the tube material is moved in a state set within the range of the equation L. (2) The method for manufacturing an internally processed heat exchanger tube according to claim 1, further comprising a fine adjustment means that can finely adjust the position of the grooved plug in the tube axis direction.